1. Field of the Invention
The present invention relates to a shock absorption in a seat, which absorbs a shock to an occupant on the seat who hits against a part of the seat, and in particular to a shock absorption arrangement provided in a seat back of automotive seat having, provided on its top, a hard control element such as a bracket and lever for operation of a reclining device for adjustment in inclination of the seat back or a mechanism for folding an upper part of the seat back to a lower part of the same.
2. Description of Prior Art
Some of various automotive seats are provided with a control element in the seat back thereof for reclining purpose or for causing the upper part of the seat back to fold onto the lower part of the same in the foldable type of seat back. As indicated in FIG. 1, such control element typically comprises an operation lever (4xe2x80x2) and a bracket (Axe2x80x2) supporting the lever, all of which are disposed at the top of a seat back (SB) adjacent to its one corner. Designation (5) denotes a well known tubular seat back frame having an upper inverted-U-shaped frame section defined therein. The bracket (Axe2x80x2) is formed from a sheet metal in a three-dimensional configuration having an integral securing portion (13xe2x80x2). As indicated by the phantom lines, this robust bracket (Axe2x80x2) is firmly welded at its securing portion (13xe2x80x2) upon the whole of one upper corner portion of such tubular seat back frame (5) which is embedded in the seat back (SB). The operation lever (4xe2x80x2) is made of a hard metallic material and movably supported in the bracket (Axe2x80x2) and may be operatively connected via a cable (3) with a reclining device (E) or with a mechanisms (D) for causing the upper part (SB1) of the seat back (SB) to fold toward the lower part (SB2) of the same. An occupant on the seat (S) can therefore operate the lever (4xe2x80x2) to incline either of the seat back (SB) and its upper part (SB1), as required.
In the foregoing known arrangement, however, it is of much likelihood that a passenger sifting on a rear seat behind the seat (S) (at R) will hit at his or her head against such very hard elements as the lever (4xe2x80x2) and bracket (Axe2x80x2) in a collision case or the like, raising a dangerous and injury problem.
Conventionally, to solve that problem, several kinds of shock absorption materials have been used and provided in the upholstery or a foam padding layer of the seat back (SB) to surround both lever (4xe2x80x2) and bracket (Axe2x80x2) so as to protect the head of an occupant on the rear seat against serious damage and injury. Also, as the seat back frame (5) itself is increasingly very hard due to various reinforcing elements provided thereto, several shock absorption arrangements have been added in the seat back frame for protection of the rear-seat passenger. But, such shock absorption has been found defective in rendering much complicated the structure of seat back, which requires troublesome and time-consuming steps in assembling the seat back and also high amount of costs involved.
In view of the above-stated drawbacks, it is therefore a purpose of the present invention to provide an improved shock absorption arrangement in the seat back of a seat, which permits direct use of the original parts of conventional bracket and lever, and effectively absorbs a shock to a person who hits his or her head thereagainst.
To achieve such purpose, in a known tubular seat back frame of a generally inverted xe2x80x9cUxe2x80x9d shape, with a bracket fixed on one curved corner thereof, the bracket having an operation lever movably provided therein, a shock absorption arrangement of the present invention is basically comprised of:
a main wall region defined in the bracket, the main wall region including a lateral side, an upper side and a lower side;
a lateral wall region so defined on the bracket as to extend from the lateral side of main wall region in a forward direction forwardly ion the seat back frame;
an upper wall region so defined in the bracket, independently of the lateral wall region, as to extend from the upper side of main wall region in the forward direction, the upper wall region having an opening formed therein, through which the operation lever passes;
a securing portion so defined in the bracket as to extend from the lower side of main wall region, the securing portion being fixed on the foregoing one curved corners at a side forwardly of the seat back; and
a stopper means fixedly provided on and over the lateral wall region and a forward part of the seat back frame, the stopper means including an abutment end portion oriented toward said operation lever, wherein said abutment end portion is so adapted that, when the bracket is deformed and bent in a forward direction by an external load applied thereto from the rearward side of seat back frame, the operation lever is abutted against the abutment end portion.
Accordingly, this arrangement can be simply constructed by directly using the conventional bracket with operation lever, at low costs. Also, if, for instance, the head of a person is hit against the bracket and lever, the whole of bracket is bent at its securing portion in the forward direction with respect to the seat back frame, thereby avoiding a direct serious impact on the head of person. Further, at this moment, the operation lever is quickly abutted against the abutment end portion of stopper means, whereby there is established a straight passage between the lever and abutment end portion, through which passage, a part of the load exerted upon both main wall region and lever is positively transmitted to both horizontal and vertical wire sections of stopper wire member. On the other hand, another part of the load, exerted on the lateral wall section, is transmitted to the vertical wire section. Consequently, if the load exceeds the rigidity of that vertical wire section, the whole of bracket is bent together with the vertical wire section forwardly relative to the seat back frame, thereby absorbing most of the impact of load.
Preferably, the stopper means may further include a first portion welded along the lateral wall region and a second portion extending from the first portion on a generally horizontal line to a point within the bracket.
The stopper means may comprise a wire member which is so formed as to define therein: a lower wire portion welded on a forward part of the seat back frame; a vertical wire portion welded on and along the lateral wall region in a generally vertical direction; and a horizontal wire portion extending from the vertical wire portion on a generally horizontal line, the horizontal wire portion terminating in the abovementioned abutment end portion within the bracket, wherein the abutment end portion is in turn oriented therefrom toward the operation lever in a direction orthogonal therewith, with a spacing provided between the abutment end portion and operation lever. The rigidity of this wire member is set to such a predetermined degree that withstands a certain normal load and only allows the wire member to be bendable by a great excessive load (L) which is applied in excess of its rigidity from the human""s head or body to both lever (4) and bracket (A).
Preferably, an opening may be formed in the securing portion so as to increase its bendability with respect to the seat back frame.